The invention relates to a method and an apparatus for recording of process parameters of reaction liquids in a plurality of microreactors, which are shaken continuously at least until the end of the reaction in all of the microreactors, with the process parameters being recorded in the microreactors during the reaction with the aid of at least one sensor optics device which introduces electromagnetic radiation from a radiation source into the reaction liquid in a microreactor, and with electromagnetic radiation which originates from the reaction liquid in the microreactor being recorded by a sensor which is associated with the radiation source.
The invention is particularly suitable for automated recording of process parameters of microbial, biochemical, enzymatic and chemical reactions in reaction liquids which are shaken without interruption until completion of the reaction in all of the microreactors.
By way of example, the biomass, substrate, product and byproduct concentrations, the self-fluorescence of cells, the fluorescence of fluorescent proteins and amino acids, pH, T, pO2 and pCO2 values, the oxygen transfer rate (OTR) and the carbon-dioxide transfer rate (CTR) can be recorded as parameters of the reaction liquids.
In particular, the above-mentioned parameters are intended to be determined in microreactors with a size of 10 μl-5 ml, in order to reduce the expense for chemical, biochemical, enzymatic and microbial optimization methods, also referred to as screening. Screening is considered, for example, for the core-area selection, media optimization and optimization of process control. The small volumes in the microreactors allow the required high throughputs in many areas of research and development, in particular such as combinational chemistry and molecular biotechnology.
So-called microtiterplate readers are known from the prior art, for recording the absorption and fluorescence in microbial reaction liquids. The shaking movement of the microtiterplates must be interrupted for each recording of process parameters during the reaction. The greater the number of process parameters that are intended to be obtained while the reactions are taking place, the more frequently the shaking movement must be interrupted, thus disturbing mixing processes and substance transport processes. This can result in anaerobic conditions in the case of cultures which cause greater or lesser damage to the various microorganisms. An absorption microtiterplate reader such as this for 200-well microtiterplates for monitoring of microbial growth is available, for example, from the Thermo Electron Corporation, Waltham, Mass., USA. The light absorption by the cells located in the wells is recorded. For this purpose, electromagnetic radiation from a radiation source is introduced into the reaction liquid in the wells, and the electromagnetic radiation emitted from the reaction liquid in the microreactor is recorded by means of a sensor. The sensor signals depend on the layer thickness passed through and on the cell concentration.
Furthermore, U.S. Pat. No. 6,673,532 B2 has already disclosed a microtiterplate reader for recording of the absorption in microbial culture liquids, in which the shaking movement of the microtiterplates need not be interrupted in order to record the absorption during the reaction. By way of example, the known apparatus comprises a microtiterplate with 96 wells, which is held by a microreactor platform. The individual wells have a volume of between 100 μl and 250 μl. At least one sensor optics device is located in a sub-platform arranged under the microreactor platform and has an excitation source, for example a light-emitting diode, as well as a detector, which records the absorption of the electromagnetic radiation from the excitation source in the reaction liquid in the microreactor (wells). The change in the measured absorption indicates a change in the concentration of the analyte in the microreactor. One refinement of the reader provides for the LEDs and the detectors to be moved from one microreactor to another by means of a robot. Another refinement provides for each microreactor to have at least one associated LED and one associated detector within the sub-platform. The sub-platform with the sensor optics device or devices is once again located on a shaking apparatus, which is mounted on a positioning table. The shaking apparatus is a specially manufactured device, in order to allow integration between the positioning table and the sub-platform. The positioning table can be moved in the XY axis direction and is used for the purpose of moving individual microreactors under a dispenser. By way of example, this known apparatus can be used to assess growth conditions for the microorganisms in culture liquids in a valid form, since it avoids the problems which occur as a result of interruption of the shaking movement.
However, the apparatus has the disadvantage of its complex design, particularly that of the shaker, which is specifically matched to the apparatus. A further disadvantage is that the sensor optics device or devices are also shaken in the sub-platform. Owing to the high shaking frequencies and the centrifugal forces associated with them it is possible for problems, and thus errors, to occur in the recording of the process parameters which, in some circumstances, make it necessary to repeat the reaction. This can result in undesirable delays, particularly in the case of series of investigations relating to microbial culture liquids, enzymatic and chemical reactions.
Against the background of this prior art, the invention is bottom on the object of specifying a method for recording of process parameters of reaction liquids in a plurality of microreactors which are shaken continuously during the reaction, and which method operates reliably. A further aim is to specify an apparatus for carrying out the method, which can be provided largely by the use of standard components and apparatuses from biotechnology.